Braking mechanism



Jan. 9; 1940. w. R. FREEMAN BRAK ING MECHAN I SM Fuga Feb. 15, 195s 2 sheets-,sheet 1 ESS Inventor Atty.

JU. 9 1940- w. R. FREEMAN l 2,186,332

BRAKING MEcHANISu I Filed Feb. 15, 193s 2 vsn@ats-#Sheet 2 frs-amas. a, 1940 s PATENT OFFICE :mamans-camisas Waiter B.. Freeman.

or to Wagner Electric Mo., a corporation of Delaware Univer-ltr cls. no.,

Corporation, St.

Lilli Application February-15, 1933, Serial No..5 ,'i'i'l.

5 Claims. (Cl. ISI-13) My invention relates to braking mechanism and more particularly to power-operated brakes which are manually controlled.

One of the objects of my invention is to pro- 5 vide a manually controlled power-operated braking system with means for preventing the release of nthe brakes from applied position notwithstanding-the manual control has been placed in a vposition to permit release of the brakes,

whereby the .operator may, without the use the manual control,

ual control is in release permitting position.

A more specific object of my' invention is provide the exhaustv port of a control valve trol of the clutch mechanism.

Other objects of my apparent from the connection with. showing a single embodiment thereof.

from appliedv position;

a schematic view of a power brake system the liquid" pressure type showing my invention embodied therein.

For m1111080. my invention as .applied to ingsystems Referring to braking -m withanactuatingarmzwmcnisconnecteaby l. with the pistonlof avpower cylinderlthelattermemberbeingpivotedto -meansofarod l maintain the brakesappiied and prevent the vehicle from rolling backward or forward after it has been stopped on an ineline.

A furthervobject of my invention is to provide the braking system with means for predetermining the amount of pressure with which the brakes will be held in lapplied position when the release preventing means is operated and the manfor a power-operated braking system with an independently operable shut-off valve under the coninvention will become following description taken in the accompanying drawings of illustration, I have disclosed being applied to power-operated braking systemsof theairorliquidpressure type having a combined follow-up and metering" control valve, or a common 3-way valve, but it istcbe understood that it may be equally well other types of power-operated brakhaving other types of control valves.

Figure 1 in detail, the numeralv 50 I indicates the usual cross shaft of a motor-vehicle which is adapted to actuate the. wheel echanisni. 'Ihe shaft I is provided a stationary' part `of the vehicle chassis. The arm 2 also has pivoted thereto a rod t which is secured to a valvecasing 1 by means of the easing bracket l. This valve casingcontains a. combined follow-up and metering valve for I controlling the application .and exhaustpf air under pressure to the cylinder 5.,v Slidably mounted in the valve casing is a rod 8 in align- 'ment with the rod t, this rod i being connected, by means of a rod 9, with the brake pedal III. 10 It is thus seen that the valvev casing 1 is supported in a suspended position on the rods 6 and I which are permitted to have relative movementv for controlling the valves within the casing. The rod l has' secured thereto an -arm II l. for controlling the two valves'within thecasing. 'I'he application valve I2 is normally biased tothelclosed position by spring Il in the application chamber Il. This application chamber is in communication with a second chamber Il by means of openings It controlled by the valve I2. The stem Aof the valve I2 extends within the chamber I5 and is provided with a piston I1v in fluid-tight relation with the walls of the chamf ber. A second spring. Il is interposed between the valve stem and the actuating arm II.

The chamber I S is connected by a fluid conduit I5' with the vpower cylinder 5 and is also in communication with the exhaust chamber II iocated on the oppodte side of the arm II. The I0 exhaust chamber Il is provided with an exhaust valve 2l normally biased toits closed position by means of the spring 2l, the exhaust valve controlling the openings 22 leading to the atmosphere through chamber 23. The exhaust valve v$8 Ilisprovidedwithastemextendingtoapoint adjacent the arm II.

The application chamber. I4 is connected', by a conduit Il, to a suitable source of power which, inthisinstancecomprisesapressuretank and an air compressor 20. This air compressor c is shown as a separate unit but may be driven` directly by the vehicle engine or by a suitable suction motor operated from the intake manifold oi the engine. y

In operation of the above described braking system, the exhaust 2l is normally held in open -position by the arm Ii when the brake pedal Il is in its inoperative position, this condition'be. ing the result of spring 21, between thegvaive 5( casing and rod I, normallybiasing the rod. and its attached arm Il toits extreme right position. .Upon actuation of the brake pedal Il to apply the'brakes, the rod l is moved relatively to the valve casing. permitting the exhaust valve Il -to f1;

close and causing the arm II to compress spring I8 and force the application valve I2 to open position, thereby. admitting iluid under pressure# 'by means of the power piston 4 and connecting rodl 6, will cause the valve casing to follow-up the movement of the rod 8, thus permitting the application valve I2 to close, the exhaust valve 20 remaining closed. Further movement of the brake pedal I will again open 'the application valve and admit additional air under pressure to the power cylinder to apply further pressure to the brakes with the same follow-up action ofthe valve casing.

When the brake pedal I Il `is released, spring 21 will 4cause ,the rod 8 to be moved relatively to the valv casing and open the exhaust valve 20 ,to release the air in the power cylinder 5, said valveremaining open until itis desired to again -apply the brakes.

The piston I1 in chambef I5 prevents an excess.-of air .under pressurek from entering the power cylinder when the application valve is open since the pressure in the chamber I will cause the piston to move to the right against the action of the spring I8, thereby closing the valveV I2. In case of failure of the power system, the 'rods is provided with shoulder 2s whereby the shaft I may be actua the brake pedal.

In 'accordance with my invention I provide the exhaust chamberls with a conduit 2 9 which is connected to a shut-off valve 30, the' ,rotatable element of which is provided with an arm 3| foi` connection with the clutch pedal .32 by means of Irod 33., .The'shut-off valve-is in open position 'when the clutch pedal is in the engaged position of the clutch. With this structure, when the clutch'pedal is moved to disengage the clutch, the

shut-off valve 30 will be closed, and if the brakes have been applied, they may be maintained in applied position without maintaining the brake pedal inapplied position for, although the exhaust valve 20 will be open, the power cylinder is prevented from exhausting to the atmosphere by means otithe shut-olf valve. If the clutch pedal has been moved to a position to disengage the clutch mechanism prior to the application of the brakes, the brakes may be applied by moving the brake pedal in the usual manner and they will be held in applied position without maintaining pressure on the brake pedal.

My invention has been found to be very useful in the operation of vehiclesprovided with poweroperated brakes for, 'through its use,I the operator may prevent his brakes from being released fromapplled position without the necessity of' maintaining his foot upon the brake pedal, thus enabling himto use his right foot to manipulate other mechanism, such, for example, as the accelerator. An example oi' its use is in starting the vehicle on an incline as the operator need only manipulate the clutch and accelerator pedals to start the vehicle without danger of the vehicle rolling backward, as would be the case if the operator were required to hold the vehicle-from rolling backward by'maintaining his right foot 0n the brake pedal.

Referring to Figure 2,.AI have shown a simplifled power system in which the. combined follow-up and metering valve" shown in Figure 1 has been replaced by a simple 3-way valve off ed directly by means of e aisasse common construction. The purpose of this gure is todisclose means whereby only a predetermined braking pressure will be maintained in the power cylinder tion. l

One of the ports of the 3way valve 34 is connected, by conduit 35; with the power cylinder5 for actuating the cross shaft I. Another of the ports of the 3-way valve is connected, by means of a conduit 36, with a source of pressure as, for example, the pressure tank shown in'Figure 1. The remaining port'is connected to shut-oft valve 3|] by conduit 31.

The arm 'of the 3-way valve is connected to a rod 38 which may or may .not be controlled by a pedal. The conduit 31 is provided with a chamber 39 in which is situated a relief valve 40 of the spring-pressed ball type, the valve controlling when the shut-oil? valve is in closed posibetween conduits 31 and 35, the pressure in the power cylinder 5 will be permitted to decrease to a. point where it will not open the valve 4I). The setting of the relief valve is such as to maintain suiiicient pressure in the power cylinder to prevent the vehicle from rolling on van incline when the. vehicleds stopped. Thus the elements of the braking system are relieved of excessive strains .from high pressures when such pressures are unnecessary. Also, with less pressure in the system,

the bakesmay be released more quickly.

In VFigure 3 I have disclosed my invention rapplied .to a power braking system which utilizes liquid pressure instead of air pressure. The 3- way control valve 34, the -power cylinder 5, and its connection to the braking system, are the same as in Figure 2. The conduit 3B, instead of leading to an air pressure tank, is connected to the liquid pressure tank t2A provided with a .spring backed piston 43. Liquid is placed under pressure in the pressure tank 42 by means of a suitable gear pump 44 driven from some movable part `of the vehicle.

sump tank 46'and the. pressure sideof the pump is in communication, by a conduit 41, with the pressure tank 42. The discharge conduit 31 for the discharge port of the 3way valve communicates with the combined shut-off` arid relief valve 48 which is in communication with the sump tank by conduit 49. ',I'he combined shut-0H and relief valve comprises a spring seated valve 50 having a valve stem 5I for permitting control of the valve by the lever 52 normally being held in open position. The rod 53 may be connected to the clutch pedal or to some other manually-controlled lever.

To apply the brakes, the 3-way valve 34 is moved to a position to place the pressure tank 42 in communication with the power cylinder 5. If it is now desired to prevent the release of the brakes without maintaining the power cylinder'in communication with the pressure cylinder, the valve 50 'is first actuation of rod 53 and then the `3wayvalve is permitted to assume the position shown,-thus placing the power cylinder in vcommunication with the sump tank by way of the combined shut-l and the rod 53,' the valve" permitted to close by proper.

l ot and relief valve. The amount of'pressure'i retained in the power cylinder is determined by the pressure of the valve spring.

Although I have disclosed the shut-of! valve as being separate from the control valve, it is to be understood that the two valves may be embodied within the same casing.

Having fully described my invention, what I claim as new and desire to secure' by Letters Patent of the United States is:

1. In a motor vehicle provided with clutch mechanism and with braking` apparatus, nuidoperated power means for actuating the brakes, a source of fluid pressure, a control valve for admitting fluid under pressure to the power means and exhausting it therefrom, an additional valve means communicating with the exhaust opening of the control valve for preventing the iluid under pressure from being exhausted from the power means notwithstanding the control valve is in an exhausting position, and means for controlling said additional means in response to a predeterminedl movement of an elementA of the clutch mechanism.

2. In a motor vehicle provided with a clutch mechanism and with braking apparatus. fluidoperated power means for actuating the brakes, a source of i'iuid pressure, control means for admitting fluid under pressure to the power means and exhausting it therefrom and comprising an application valve. and an exhaust valve, a conduit leadingfrom the exhaust valve to the atmosphere, a valve in said conduit, and means for closing said last named valve in response to a predetermined movement of an element of the clutch mechanism.4

3. In a ,motor vehicle provided with a clutch and' with braking apparatus, duid-operated power means for actuating the brakes. a source lnuid under pressure is actuated.

of iluld pressure,'a control valve for admitting to the power means and exhausting it therefrom, and additional valve means including-a.pressure relief valve for preventing the fluid under pressure in the .power means from being exhausted to a point below a predetermined pressure notwithstanding the control valve is in an exhausting position, said additional valve means being operable when the clutch 4. In a motor vehicle p and with braking apparatus', fluid-operated power means for actuating the brakes, a source of fluid pressure, a control valve for admitting fluid under pressure to lthe power means and exhausting it therefrom, a shut-ofi.' valve in communication with the exhaust opening of the control valve, means for controlling the shut-oi! valve when the clutch is operated, and means comprising a relief valve in communication with the exhaust openins.

5. InI a motor vehicle provided with a clutch and with braking apparatus, duid-operated power means for actuating the brakes, a source of i'luid pressure, control means for admitting fluid under pressure to the power means and exhausting it therefrom and comprising an application valve and an exhaust va1ve, a conduit -leading from the exhaust valve tothe atmosphere, a shut-off valve in said conduit, means for closing said shutoi! valve in response to a predetermined movement of an element of the clutch mechanism, and

revised with a clutch means comprising a relief valve for providing communication between the conduit and the atmosphere when the shut-on` valve is closed and thefiuidpressure inthe conduitisaboveapredetermined value.

, WALTIR R. IIRmIAN. 

